straight line stepper based on Surface intersection More...

#include <Acts/Propagator/StraightLineStepper.hpp>

Classes
struct	Config
struct	Options
struct	State
	State for track parameter propagation. More...

Public Types
using	BField = NullBField
	Type alias for magnetic field (null field for straight line propagation).
using	BoundState = std::tuple<BoundTrackParameters, Jacobian, double>
	Type alias for bound state containing parameters, jacobian, and path length.
using	Covariance = BoundSquareMatrix
	Type alias for covariance matrix.
using	Jacobian = BoundMatrix
	Type alias for transport jacobian matrix.

Public Member Functions
double	absoluteMomentum (const State &state) const
	Absolute momentum accessor.
Result< BoundState >	boundState (State &state, const Surface &surface, bool transportCov=true, const FreeToBoundCorrection &freeToBoundCorrection=FreeToBoundCorrection(false)) const
	Create and return the bound state at the current position.
double	charge (const State &state) const
	Charge access.
BoundState	curvilinearState (State &state, bool transportCov=true) const
	Create and return a curvilinear state at the current position.
Vector3	direction (const State &state) const
	Momentum direction accessor.
Result< Vector3 >	getField (State &, const Vector3 &) const
	Get the field for the stepping, this gives back a zero field.
double	getStepSize (const State &state, ConstrainedStep::Type stype) const
	Get the step size.
void	initialize (State &state, const BoundTrackParameters &par) const
	Initialize the stepper state from bound track parameters.
void	initialize (State &state, const BoundVector &boundParams, const std::optional< BoundMatrix > &cov, ParticleHypothesis particleHypothesis, const Surface &surface) const
	Initialize the stepper state from bound parameters and components.
State	makeState (const Options &options) const
	Create a stepper state from propagation options.
Vector3	momentum (const State &state) const
	Momentum accessor.
std::string	outputStepSize (const State &state) const
	Output the Step Size - single component.
const ParticleHypothesis &	particleHypothesis (const State &state) const
	Particle hypothesis.
Vector3	position (const State &state) const
	Global particle position accessor.
bool	prepareCurvilinearState (State &state) const
	If necessary fill additional members needed for curvilinearState.
double	qOverP (const State &state) const
	QoP direction accessor.
void	releaseStepSize (State &state, ConstrainedStep::Type stype) const
	Release the Step size.
Result< double >	step (State &state, Direction propDir, const IVolumeMaterial *material) const
	Perform a straight line propagation step.
double	time (const State &state) const
	Time access.
void	transportCovarianceToBound (State &state, const Surface &surface, const FreeToBoundCorrection &freeToBoundCorrection=FreeToBoundCorrection(false)) const
	Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.
void	transportCovarianceToCurvilinear (State &state) const
	Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.
void	update (State &state, const FreeVector &freeParams, const BoundVector &boundParams, const Covariance &covariance, const Surface &surface) const
	Method to update a stepper state to the some parameters.
void	update (State &state, const Vector3 &uposition, const Vector3 &udirection, double qop, double time) const
	Method to update the stepper state.
void	updateStepSize (State &state, const NavigationTarget &target, Direction direction, ConstrainedStep::Type stype) const
	Update step size.
void	updateStepSize (State &state, double stepSize, ConstrainedStep::Type stype) const
	Update step size - explicitly with a double.
IntersectionStatus	updateSurfaceStatus (State &state, const Surface &surface, std::uint8_t index, Direction navDir, const BoundaryTolerance &boundaryTolerance, double surfaceTolerance, ConstrainedStep::Type stype, const Logger &logger=getDummyLogger()) const
	Update surface status.

Detailed Description

straight line stepper based on Surface intersection

The straight line stepper is a simple navigation stepper to be used to navigate through the tracking geometry. It can be used for simple material mapping, navigation validation

Member Typedef Documentation

◆ BField

using Acts::StraightLineStepper::BField = NullBField

Type alias for magnetic field (null field for straight line propagation).

◆ BoundState

using Acts::StraightLineStepper::BoundState = std::tuple<BoundTrackParameters, Jacobian, double>

Type alias for bound state containing parameters, jacobian, and path length.

◆ Covariance

using Acts::StraightLineStepper::Covariance = BoundSquareMatrix

Type alias for covariance matrix.

◆ Jacobian

using Acts::StraightLineStepper::Jacobian = BoundMatrix

Type alias for transport jacobian matrix.

Member Function Documentation

◆ absoluteMomentum()

double Acts::StraightLineStepper::absoluteMomentum ( const State & state ) const

Absolute momentum accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Absolute momentum magnitude

◆ boundState()

Result< BoundState > Acts::StraightLineStepper::boundState	(	State &	state,
		const Surface &	surface,
		bool	transportCov = true,
		const FreeToBoundCorrection &	freeToBoundCorrection = FreeToBoundCorrection(false) ) const

Create and return the bound state at the current position.

It does not check if the transported state is at the surface, this needs to be guaranteed by the propagator

Parameters

[in]	state	State that will be presented as `BoundState`
[in]	surface	The surface to which we bind the state
[in]	transportCov	Flag steering covariance transport
[in]	freeToBoundCorrection	Correction for non-linearity effect during transform from free to bound

Returns

A bound state:

the parameters at the surface
the stepwise jacobian towards it (from last bound)
and the path length (from start - for ordering)

◆ charge()

double Acts::StraightLineStepper::charge ( const State & state ) const

Charge access.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Electric charge of the particle

◆ curvilinearState()

BoundState Acts::StraightLineStepper::curvilinearState	(	State &	state,
		bool	transportCov = true ) const

Create and return a curvilinear state at the current position.

This creates a curvilinear state.

Parameters

[in]	state	State that will be presented as `CurvilinearState`
[in]	transportCov	Flag steering covariance transport

Returns

A curvilinear state:

the curvilinear parameters at given position
the stepweise jacobian towards it (from last bound)
and the path length (from start - for ordering)

◆ direction()

Vector3 Acts::StraightLineStepper::direction ( const State & state ) const

Momentum direction accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current normalized direction vector

◆ getField()

Result< Vector3 > Acts::StraightLineStepper::getField	(	State &	,
		const Vector3 &	) const

Get the field for the stepping, this gives back a zero field.

Returns: Always returns zero magnetic field vector for straight-line propagation

◆ getStepSize()

double Acts::StraightLineStepper::getStepSize	(	const State &	state,
		ConstrainedStep::Type	stype ) const

Get the step size.

Parameters

state	[in] The stepping state (thread-local cache)
stype	[in] The step size type to be returned

Returns: Current step size for the specified constraint type

◆ initialize() [1/2]

void Acts::StraightLineStepper::initialize	(	State &	state,
		const BoundTrackParameters &	par ) const

Initialize the stepper state from bound track parameters.

Parameters

state	The stepper state to initialize
par	The bound track parameters to initialize from

◆ initialize() [2/2]

void Acts::StraightLineStepper::initialize	(	State &	state,
		const BoundVector &	boundParams,
		const std::optional< BoundMatrix > &	cov,
		ParticleHypothesis	particleHypothesis,
		const Surface &	surface ) const

Initialize the stepper state from bound parameters and components.

Parameters

state	The stepper state to initialize
boundParams	The bound parameter vector
cov	Optional covariance matrix
particleHypothesis	The particle hypothesis (mass, charge, etc.)
surface	The reference surface

◆ makeState()

State Acts::StraightLineStepper::makeState ( const Options & options ) const

Create a stepper state from propagation options.

Parameters

options The propagation options

Returns: A new stepper state initialized with the provided options

◆ momentum()

Vector3 Acts::StraightLineStepper::momentum ( const State & state ) const

Momentum accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current momentum vector

◆ outputStepSize()

std::string Acts::StraightLineStepper::outputStepSize ( const State & state ) const

Output the Step Size - single component.

Parameters

state [in,out] The stepping state (thread-local cache)

Returns: String representation of the current step size

◆ particleHypothesis()

const ParticleHypothesis & Acts::StraightLineStepper::particleHypothesis ( const State & state ) const

Particle hypothesis.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Reference to the particle hypothesis used

◆ position()

Vector3 Acts::StraightLineStepper::position ( const State & state ) const

Global particle position accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Current global position vector

◆ prepareCurvilinearState()

bool Acts::StraightLineStepper::prepareCurvilinearState ( State & state ) const

If necessary fill additional members needed for curvilinearState.

Compute path length derivatives in case they have not been computed yet, which is the case if no step has been executed yet.

Parameters

[in,out] state The stepping state (thread-local cache)

Returns: true if nothing is missing after this call, false otherwise.

◆ qOverP()

double Acts::StraightLineStepper::qOverP ( const State & state ) const

QoP direction accessor.

Parameters

state [in] The stepping state (thread-local cache)

Returns: Charge over momentum (q/p) value

◆ releaseStepSize()

void Acts::StraightLineStepper::releaseStepSize	(	State &	state,
		ConstrainedStep::Type	stype ) const

Release the Step size.

Parameters

[in,out]	state	The stepping state (thread-local cache)
[in]	stype	The step size type to be released

◆ step()

Result< double > Acts::StraightLineStepper::step	(	State &	state,
		Direction	propDir,
		const IVolumeMaterial *	material ) const

Perform a straight line propagation step.

Parameters

[in,out]	state	State of the stepper
	propDir	is the direction of propagation
	material	is the optional volume material we are stepping through.

Returns: the result of the step

Note: The state contains the desired step size. It can be negative during backwards track propagation.

◆ time()

double Acts::StraightLineStepper::time ( const State & state ) const

Time access.

Parameters

state [in] The stepping state (thread-local cache)

Returns: The time coordinate from the free parameters vector

◆ transportCovarianceToBound()

void Acts::StraightLineStepper::transportCovarianceToBound	(	State &	state,
		const Surface &	surface,
		const FreeToBoundCorrection &	freeToBoundCorrection = FreeToBoundCorrection(false) ) const

Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.

Template Parameters

surface_t the surface type - ignored here

Parameters

[in,out]	state	The stepper state
[in]	surface	is the surface to which the covariance is forwarded to

Note: no check is done if the position is actually on the surface

Parameters

[in] freeToBoundCorrection Correction for non-linearity effect during transform from free to bound

◆ transportCovarianceToCurvilinear()

void Acts::StraightLineStepper::transportCovarianceToCurvilinear ( State & state ) const

Method for on-demand transport of the covariance to a new curvilinear frame at current position, or direction of the state - for the moment a dummy method.

Parameters

[in,out] state State of the stepper

◆ update() [1/2]

void Acts::StraightLineStepper::update	(	State &	state,
		const FreeVector &	freeParams,
		const BoundVector &	boundParams,
		const Covariance &	covariance,
		const Surface &	surface ) const

Method to update a stepper state to the some parameters.

Parameters

[in,out]	state	State object that will be updated
[in]	freeParams	Free parameters that will be written into `state`
[in]	boundParams	Corresponding bound parameters used to update jacToGlobal in `state`
[in]	covariance	Covariance that will be written into `state`
[in]	surface	The surface used to update the jacToGlobal

◆ update() [2/2]

void Acts::StraightLineStepper::update	(	State &	state,
		const Vector3 &	uposition,
		const Vector3 &	udirection,
		double	qop,
		double	time ) const

Method to update the stepper state.

Parameters

[in,out]	state	State object that will be updated
[in]	uposition	the updated position
[in]	udirection	the updated direction
[in]	qop	the updated qop value
[in]	time	the updated time value

◆ updateStepSize() [1/2]

void Acts::StraightLineStepper::updateStepSize	(	State &	state,
		const NavigationTarget &	target,
		Direction	direction,
		ConstrainedStep::Type	stype ) const

Update step size.

It checks the status to the reference surface & updates the step size accordingly

Parameters

state	[in,out] The stepping state (thread-local cache)
target	[in] The NavigationTarget
direction	[in] The propagation direction
stype	[in] The step size type to be set

◆ updateStepSize() [2/2]

void Acts::StraightLineStepper::updateStepSize	(	State &	state,
		double	stepSize,
		ConstrainedStep::Type	stype ) const

Update step size - explicitly with a double.

Parameters

state	[in,out] The stepping state (thread-local cache)
stepSize	[in] The step size value
stype	[in] The step size type to be set

◆ updateSurfaceStatus()

IntersectionStatus Acts::StraightLineStepper::updateSurfaceStatus	(	State &	state,
		const Surface &	surface,
		std::uint8_t	index,
		Direction	navDir,
		const BoundaryTolerance &	boundaryTolerance,
		double	surfaceTolerance,
		ConstrainedStep::Type	stype,
		const Logger &	logger = getDummyLogger() ) const

Update surface status.

This method intersects the provided surface and update the navigation step estimation accordingly (hence it changes the state). It also returns the status of the intersection to trigger onSurface in case the surface is reached.

Parameters

[in,out]	state	The stepping state (thread-local cache)
[in]	surface	The surface provided
[in]	index	The surface intersection index
[in]	navDir	The navigation direction
[in]	boundaryTolerance	The boundary check for this status update
[in]	surfaceTolerance	Surface tolerance used for intersection
[in]	stype	The step size type to be set
[in]	logger	A logger instance

Returns: Status of the intersection indicating whether surface was reached

Classes

Public Types

Public Member Functions

Detailed Description

Member Typedef Documentation

◆ BField

◆ BoundState

◆ Covariance

◆ Jacobian

Member Function Documentation

◆ absoluteMomentum()

◆ boundState()

◆ charge()

◆ curvilinearState()

◆ direction()

◆ getField()

◆ getStepSize()

◆ initialize() [1/2]

◆ initialize() [2/2]

◆ makeState()

◆ momentum()

◆ outputStepSize()

◆ particleHypothesis()

◆ position()

◆ prepareCurvilinearState()

◆ qOverP()

◆ releaseStepSize()

◆ step()

◆ time()

◆ transportCovarianceToBound()

◆ transportCovarianceToCurvilinear()

◆ update() [1/2]

◆ update() [2/2]

◆ updateStepSize() [1/2]

◆ updateStepSize() [2/2]

◆ updateSurfaceStatus()